/**
* Read value from database file, returning a pointer to the allocated
* deserialized data. These data can be modified freely and stored back,
* but their lifetime will not exceed that of the next call to a dbmw
* operation on the same descriptor.
*
* User code does not need to bother with freeing the allocated data, this
* is managed directly by the DBM wrapper.
*
* @param dw the DBM wrapper
* @param key the key (constant-width, determined at open time)
* @param lenptr if non-NULL, writes length of (deserialized) value
*
* @return pointer to value, or NULL if it was either not found or the
* deserialization failed.
*/
G_GNUC_HOT gpointer
dbmw_read(dbmw_t *dw, gconstpointer key, size_t *lenptr)
{
struct cached *entry;
dbmap_datum_t dval;
dbmw_check(dw);
g_assert(key);
dw->r_access++;
entry = map_lookup(dw->values, key);
if (entry) {
dw->r_hits++;
if (lenptr)
*lenptr = entry->len;
return entry->data;
}
/*
* Not cached, must read from DB.
*/
dw->ioerr = FALSE;
dval = dbmap_lookup(dw->dm, key);
if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
g_warning("DBMW \"%s\" I/O error whilst reading entry: %s",
dw->name, dbmap_strerror(dw->dm));
return NULL;
} else if (NULL == dval.data)
return NULL; /* Not found in DB */
/*
* Value was found, allocate a cache entry object for it.
*/
WALLOC0(entry);
/*
* Deserialize data if needed.
*/
if (dw->unpack) {
/*
* Allocate cache entry arena to hold the deserialized version.
*/
entry->data = walloc(dw->value_size);
entry->len = dw->value_size;
bstr_reset(dw->bs, dval.data, dval.len, BSTR_F_ERROR);
if (!dbmw_deserialize(dw, dw->bs, entry->data, dw->value_size)) {
g_carp("DBMW \"%s\" deserialization error in %s(): %s",
dw->name,
stacktrace_routine_name(func_to_pointer(dw->unpack), FALSE),
bstr_error(dw->bs));
/* Not calling value free routine on deserialization failures */
wfree(entry->data, dw->value_size);
WFREE(entry);
return NULL;
}
if (lenptr)
*lenptr = dw->value_size;
} else {
g_assert(dw->value_size >= dval.len);
if (dval.len) {
entry->len = dval.len;
entry->data = wcopy(dval.data, dval.len);
} else {
entry->data = NULL;
entry->len = 0;
}
if (lenptr)
*lenptr = dval.len;
}
g_assert((entry->len != 0) == (entry->data != NULL));
/*
* Insert into cache.
*/
(void) allocate_entry(dw, key, entry);
return entry->data;
}
/**
* Read value from database file, returning a pointer to the allocated
* deserialized data. These data can be modified freely and stored back,
* but their lifetime will not exceed that of the next call to a dbmw
* operation on the same descriptor.
*
* User code does not need to bother with freeing the allocated data, this
* is managed directly by the DBM wrapper.
*
* @param dw the DBM wrapper
* @param key the key (constant-width, determined at open time)
* @param lenptr if non-NULL, writes length of (deserialized) value
*
* @return pointer to value, or NULL if it was either not found or the
* deserialization failed.
*/
G_GNUC_HOT void *
dbmw_read(dbmw_t *dw, const void *key, size_t *lenptr)
{
struct cached *entry;
dbmap_datum_t dval;
dbmw_check(dw);
g_assert(key);
dw->r_access++;
entry = map_lookup(dw->values, key);
if (entry) {
if (dbg_ds_debugging(dw->dbg, 5, DBG_DSF_CACHING | DBG_DSF_ACCESS)) {
dbg_ds_log(dw->dbg, dw, "%s: read cache hit on %s key=%s%s",
G_STRFUNC, entry->dirty ? "dirty" : "clean",
dbg_ds_keystr(dw->dbg, key, (size_t) -1),
entry->absent ? " (absent)" : "");
}
dw->r_hits++;
if (lenptr)
*lenptr = entry->len;
return entry->data;
}
/*
* Not cached, must read from DB.
*/
dw->ioerr = FALSE;
dval = dbmap_lookup(dw->dm, key);
if (dbmap_has_ioerr(dw->dm)) {
dw->ioerr = TRUE;
dw->error = errno;
s_warning_once_per(LOG_PERIOD_SECOND,
"DBMW \"%s\" I/O error whilst reading entry: %s",
dw->name, dbmap_strerror(dw->dm));
return NULL;
} else if (NULL == dval.data)
return NULL; /* Not found in DB */
/*
* Value was found, allocate a cache entry object for it.
*/
WALLOC0(entry);
/*
* Deserialize data if needed.
*/
if (dw->unpack) {
/*
* Allocate cache entry arena to hold the deserialized version.
*/
entry->data = walloc(dw->value_size);
entry->len = dw->value_size;
bstr_reset(dw->bs, dval.data, dval.len, BSTR_F_ERROR);
if (!dbmw_deserialize(dw, dw->bs, entry->data, dw->value_size)) {
s_critical("DBMW \"%s\" deserialization error in %s(): %s",
dw->name, stacktrace_function_name(dw->unpack),
bstr_error(dw->bs));
/* Not calling value free routine on deserialization failures */
wfree(entry->data, dw->value_size);
WFREE(entry);
return NULL;
}
if (lenptr)
*lenptr = dw->value_size;
} else {
g_assert(dw->value_size >= dval.len);
if (dval.len) {
entry->len = dval.len;
entry->data = wcopy(dval.data, dval.len);
} else {
entry->data = NULL;
entry->len = 0;
}
if (lenptr)
*lenptr = dval.len;
}
g_assert((entry->len != 0) == (entry->data != NULL));
/*
* Insert into cache.
*/
(void) allocate_entry(dw, key, entry);
if (dbg_ds_debugging(dw->dbg, 4, DBG_DSF_CACHING)) {
dbg_ds_log(dw->dbg, dw, "%s: cached %s key=%s%s",
G_STRFUNC, entry->dirty ? "dirty" : "clean",
dbg_ds_keystr(dw->dbg, key, (size_t) -1),
entry->absent ? " (absent)" : "");
}
return entry->data;
}
